The United States Coast Guard (USCG) plays an integral role in NOAA’s charting program. Nine USCG districts throughout the country publish chart corrections weekly in “Local Notice to Mariners” (LNM). The LNM and the Notice to Mariners (published by the National Geospatial-Intelligence Agency (NGA)) are the primary sources used by mariners to keep their charts updated.

NOAA cartographers and individuals from local Coast Guard districts work closely together to ensure accurate chart update information is provided to mariners on a weekly basis. Initially, each agency may receive potential chart update information independently from a variety of sources. For the Coast Guard’s part, individual districts compile information pertaining to additions, deletions or changes to aids to navigation. The Coast Guard also is involved in relocation of traffic separation schemes that ultimately must be updated on nautical charts. Coast Guard units also receive chart discrepancy reports directly from local sources; for example, shoaling, wrecks, and other features that might affect the chart are often reported to the local Coast Guard but not reported to NOAA.

NOAA regularly receives chart update information from a variety of sources that the Coast Guard might not be aware of initially. For example, NOAA receives dredge or condition channel surveys from the USACE. Cartographers create updated channel tabulations and legends and forward this information their Coast Guard LNM contacts. In addition, NOAA may receive information directly about shoaling, wrecks, or obstructions; information that initially might not have been reported to the Coast Guard. If this new information is “critical”, NOAA cartographers will furnish it to the appropriate Coast Guard District for publication in the LNM. NOAA provides the USCG with over 50 percent of the chart updates found in LNMs. The final LNM that is published is a conglomeration of information that either entered the chart update system through a NOAA or USCG pipeline.

NOAA and the Coast Guard are committed to creating a seamless medium for the exchange of chart update information. Each week, NOAA cartographers provide the Coast Guard with chart updates in a format that can easily be imported into the Coast Guard’s LNM electronic format. Before publishing LNMs weekly on the Internet and on paper, individual Coast Guard districts typically will provide NOAA cartographers with an advanced electronic version. NOAA cartographers will perform a preliminary application (via computer) to their master chart to ensure there are no errors. The Coast Guard then makes the LNM available on its Internet site and a few days later, on paper.

NOAA and the Coast Guard have worked together over the last several years to ensure their respective navigation databases are consistent and accurate. In the age of electronic navigation, it is important that the positions of aids to navigation and other geographic features are known precisely and these positions be incorporated into electronic charting databases. The Coast Guard’s Light List serves as the ultimate authority for aids to navigation information. NOAA and the Coast Guard have been working to ensure that NOAA’s electronic charting database is consistent with the Coast Guard’s Light List database.

The Coast Guard is also responsible for maintaining a database that tracks important vertical and horizontal information about bridges. The Coast Guard provides this information to NOAA on a regular basis so that affected charts can be updated.